1. Field of Invention
This invention relates to baffles employed in cam covers of motor vehicle engines, and more particularly, to methods and materials for isolating the baffles from vibrations transmitted through the cam covers.
2. Discussion
Cam cover baffles used in motor vehicle engines aid in the removal of oil mist entrained in crankcase gases and are designed to optimize crankcase airflow through the cam (valve) cover. Conventional cam cover baffles are typically formed of a thin, single layer of stamped metal, such as steel. One problem with such baffle designs is that engine vibrations may cause the metal layer to resonate, resulting in undesirable noise generation. Designers have employed several techniques for resolving noise and vibration issues, including applying energy dissipating coatings on the metal layer.
Although baffle designs employing energy dissipating coatings have met with some success, the use of coatings creates other problems. For example, coatings add mass, and increase the material costs and labor associated with manufacturing the baffle. Additionally, it is often difficult to accurately control the thickness of the coating, which may result in sealing difficulties between the baffle and the cam cover and may lead to improper control of PCV emissions. Furthermore, portions of the coating may detach from the baffle during engine operation, which may contaminate the crankcase.
The present invention overcomes, or at least helps reduce the effects of one or more of the problems set forth above.
The present invention provides a baffle that is adapted for use in an interior of a cam cover, which addresses many of the problems described above. The baffle includes a base layer, which is made of metal, and an isolation layer that is comprised of a resilient foam. The isolation layer is disposed on a surface of the base layer in a pattern that leaves uncovered a portion of the surface of the base layer. When the baffle is installed in the cam cover, the isolation layer provides an interface between the base layer and the cam cover, thereby isolating the baffle from vibrations in the cam cover.
Another aspect of the invention provides a baffle that is adapted for use in an interior of a cam cover, which includes first and second structural layers, and a viscoelastic adhesive layer that is interposed between the two structural layers. The baffle also includes an isolation layer that is comprised of a resilient foam, which is disposed on a surface of the first structural layer in a pattern that leaves uncovered a portion of the surface of the first structural layer. The isolation layer provides an interface between the first structural layer and the cam cover when the baffle is installed in the interior of the cam cover.
Still another aspect of the invention provides a method of making a baffle for a cam cover. The method comprises providing a structural layer and applying an isolation layer on a surface of the structural layer in a pattern that leaves uncovered a portion of the surface of the structural layer. The isolation layer is comprised of a resilient foam, which dampens vibrations transmitted through the cam cover. In addition to providing improved vibration isolation, the inventive baffle and method use less materials and labor than conventional baffle manufacturing processes since the isolation layer is applied only where it is needed. Because the isolation layer does not completely cover the surface of the structural layer, and for the most part is sandwiched between the structural layer and the cam cover, there is less chance that the foamed material will detach from the baffle.